There are several methods for assessing and describing the presence of excess weight. However, most authorities now define excess weight in terms of the Body Mass Index (BMI). The BMI is calculated by dividing the weight in kilograms by the square of the height in meters. For example, a 1.75 m tall man who weighs 85 kg has a BMI of 85/(1.75)2 or 85/3.0625=28. A person with a height of 1.6 m having the same weight will have a BMI of 33. Individuals are considered to suffer from morbid obesity if their BMI is ≧40.0 or if their BMI has a value of 35.0-39.9 and they suffer from obesity related medical problems.
In earlier times, being obese was considered a sign of good health. However, it is now clear that obesity is associated with a number of serious conditions, and that it is a major health risk, whose prevalence is rising. Overweight and obesity are known risk factors for: diabetes, heart disease, stroke, hypertension, gallbladder disease, osteoarthritis, sleep apnea and other breathing problems, and some forms of cancer (uterine, breast, colorectal, kidney, and gallbladder). In addition obesity is associated with: high blood cholesterol, complications of pregnancy, menstrual irregularities, hirsutism, stress urinary incontinence, psychological disorders such as depression, and increased surgical risk.
It is evident then that obesity is a major health problem and is now considered an epidemic in the western world and is beginning to be a serious problem in areas of the world where it has traditionally been virtually unknown. The prevalence of obesity in many western countries is alarmingly high. For example, from data available for 1999, over ten million people suffered from morbid obesity, as defined above, in the United States of America and the deaths of an estimated 300,000 to 600,000 people could be related to obesity.
Despite these facts, many people regard obesity as being due to lack of will power and that it is solely due to bad eating habits and lack of exercise. The consensus amongst health care professionals today however is that obesity is a disease in its own right. As summarized by the National Institutes of Health in 1985 [Health Implications of Obesity. NIH Consensus Statement Online 1985 Feb. 11-13; 5(9):1-7];
Formerly, obesity was considered fully explained by the single adverse behavior of inappropriate eating in the setting of attractive foods. The study of animal models of obesity, biochemical alterations in man and experimental animals, and the complex interactions of psychosocial and cultural factors that create susceptibility to human obesity indicate that this disease in man is complex and deeply rooted in biologic systems. Thus, it is almost certain that obesity has multiple causes and that there are different types of obesity.
Physical inactivity and nutrition are only two of many causal factors of obesity, as the disease is currently understood. Other factors are genetic predisposition, environmental factors (social and cultural), physiologic and metabolic factors, behavioral, and psychological conditions. There is no question that physical activity and nutrition are factors in the development, management and prevention of obesity. However, research is progressively increasing our understanding of the critical roles played by genetic factors and psychological factors. “The belief that obesity is largely the result of a lack of willpower, though widely held, is unsatisfactory. Studies of twins, analyses of familial aggregation, adoption studies and animal models of obesity all indicate that obesity is the result of a high percentage of genetic as well as of environmental factors.” [Friedman J M, Leptin and the Regulation of Body Weight in Mammals. Nature, 1998; 395:763-770].
To summarize present day thinking, obesity is a disease in its own right, and that treatment strategies should (and are) be developed to combat it.
Current treatment options for obesity include both non-surgical and surgical methods. Non-surgical approaches to treatment of clinically severe obesity include various combinations of low- or very low-calorie diets, behavioral modification, exercise, and pharmacologic agents.
The obvious solution to obesity is to eat less. It is quite obvious that less food intake will result is weight loss. However, diet in many forms has proven inadequate to control obesity particularly in morbid obesity. Significant weight reduction, for example 20 kg over 12 weeks, can be expected. However, in the absence of successful behavior modification, most patients regain their lost weight within 1 year. Additionally, medical complications of rapid weight loss may occur. These are usually treatable if recognized and their occurrence can be limited by proper medical supervision. Behavioral modification is a therapeutic approach based on the assumption that habitual eating and physical activity behaviors must be relearned to promote long-term weight change. Behavioral treatment also can be combined with a lesser degree of caloric restriction, although evidence of long-term efficacy of this more conservative approach in persons with clinically severe obesity is lacking. Increased physical activity is recommended as a component of weight-loss programs; however, the role of exercise in promoting and sustaining weight loss has never been established. Experience with drug therapy for clinically severe obesity has been disappointing. Although pharmacologic studies with anorexigenic drugs suggest short-term benefit, prolonged and sustained weight loss has not been proved with these agents. The general weight of the evidence that has been obtained in recognized clinical trials is that only in rare cases of a highly disciplined and motivated patient has safe long term weight loss been achieved by non-surgical methods of treatment of morbid obesity.
Various surgical approaches to morbid obesity have been tried over the years. In general, the surgical techniques can be regarded as either malabsorptive or restrictive.
Malabsorptive procedures modify the gastrointestinal tract so that only a small fraction of the food intake is actually digested. Following a malabsorptive procedure, the patient can continue to gorge himself, but the food is not fully digested, and the amount of calories and nutrients absorbed is small.
Restrictive procedures work by limiting food intake. Following a restrictive procedure, the patient's ability to eat is severely restricted. The patient can only eat a limited amount of food. Any attempt to eat more, will result in varying degrees of discomfort. In addition to forcing the patient to eat less, the discomfort conditions the patient to chew his food well, and obtain healthier eating habits, which may outlive the restriction in certain cases.
It is possible to combine restrictive and malabsorptive procedures, and achieve greater weight loss. The leading bariatric procedure in the US right now is Roux en Y Gastric Bypass which combines stomach restriction with malabsorption, which is achieved by bypassing the proximal small intestine.
In general, malabsorptive procedures are usually more technically challenging and result in greater weight loss. The first malabsorptive procedure, called the Jejuno-ileal bypass, was associated with so many late complications that it is now abandoned. The main malabsorptive operations currently performed are the Scopinaro Biliopancreatic Bypass and the Duodenal Switch procedure. In competent hands these are highly successful operations.
The restrictive procedures that are currently being used or have been practiced in the past include:                Jaw wiring is a method for restricting weight by wiring the jaws shut. After jaw wiring, the patients can only take fluids with a straw. This usually results in significant weight loss. However, almost all patients regain their weight soon after the wires are removed. In addition, a high percentage of patients cannot tolerate the wires, and request to have them removed or remove them by themselves [Ramsey-Stewart G, Martin. L: Jaw wiring in the treatment of morbid obesity. Aust N Z J Surg 1985 April; 55(2):163-7].        Because of these limitations, jaw wiring is no longer a commonly offered option to patients. A Medline search for Jaw wiring and obesity showed that no articles on Jaw wiring as a treatment for morbid obesity had been published since 1985. The last paper, published in 1993, showed that using jaw wiring as a prelude to bariatric operation did not influence the long-term weight loss, when compared to controls.        The Intragastric balloon, sometimes known as the gastric bubble, was introduced in the late 1980's as a non-invasive method for treating obesity. There are a number of commercially available balloons, usually made of silicone rubber. They are placed in the stomach by oral endoscopy, and inflated to 400-600 ml. The idea being that the balloon fills the stomach, restricting its volume, and at the same time produces a sensation of satiety. Attractive as it seemed at the time of its introduction, and in spite of a few early clinical trials showing weight loss, a number of randomized controlled trials failed to show its efficacy.        Even in the early clinical trials, the benefit observed disappeared quickly, even if the balloon was maintained inflated. From these results it is evident that the intragastric balloon is not a good solution to the problem of obesity, although it may have a useful role in interim management of selected patients.        Horizontal gastroplasty, developed by Gomez in Ohio in 1979, was the first attempt at a gastric restrictive operation. The early use of stapling devices in obesity surgery involved removal of three staples from the row and firing the stapler across the top part of the stomach. As a result, the two stomach walls are stapled together, except at the point where the three staples were removed, where a small gap remains. The idea being that food, which the patient takes in, is retained in the segment of stomach above the staple line causing the sensation of fullness. The food then empties slowly through the gap (stoma) into the part of the stomach below the staple line where digestion takes place normally.        Early results were very encouraging. They showed that the food in the small pouch indeed produced a sensation of satiety and that the patients lost weight rapidly. Unfortunately, the muscular stomach wall has a tendency to stretch and the stoma enlarges. Sometimes the staple line failed. To combat these problems, other procedures in which the stoma was moved to the side and reinforced were introduced. Because the procedures discussed below had better long-term results, horizontal gastroplasty fell out of favor and is now practically abandoned. However, the results of horizontal gastroplasty are still much better than the results of non-surgical treatment, intra-gastric balloon, or jaw wiring.        Vertical banded gastroplasty (VBG) was introduced by Dr. Edward Mason, Professor of Surgery at the University of Iowa, in 1982 to overcome the shortcomings of horizontal gastroplasty described above. Mason realized that the lesser curvature part of the stomach had the thickest wall and was therefore least likely to stretch; therefore he used a vertical segment of stomach along the lesser curvature for the pouch. Additionally, he was very meticulous in defining the size of the pouch, measuring it at surgery under a standard hydrostatic pressure, and has shown that best results follow the use of a very small pouch, holding only 14 cc saline at the time of surgery. The third modification which he made was to place a polypropylene band (Marlex Mesh) around the lower end of the vertical pouch, which acts as the stoma, to fix the size of the outlet of the pouch preventing it from stretching. This is done by use of a circular stapling instrument to staple the front and back walls of the stomach together, cutting out a circular window to allow the polypropylene band to be placed around the lower end of the pouch. His extensive studies showed that the correct circumference of the band is 5.0 cm. Correctly performed this operation produces good weight loss results. There are few complications associated with Vertical Banded Gastroplasty, because all food taken in is digested normally. Anemia is rare and vitamin B12 deficiency is almost unknown. The patient does have to be very careful to chew food completely to avoid vomiting, and to avoid high calorie liquids such as regular sodas and ice cream. A surgical variant of the VBG is the Silastic Ring Vertical Gastroplasty (SRVG), which is functionally identical to VBG but uses a silastic ring to control the stoma size. These procedures were mostly abandoned due to weight regain caused by gradual opening of the staple line. Surgeons who previously performed VBG or SRVG migrated to the more contemporary and successful RYGB and AGB (see below).        Roux-en-Y Gastric Bypass (RYGB) was also developed by Dr Edward E. Mason, of the University of Iowa. It is mainly a restrictive procedure, but also causes some malabsorption. Its evolution since its introduction in 1967 is quite convoluted, but it is an operation that has endured the test of time. With one series of greater than 500 cases, followed for 14 years, maintaining 50% excess weight loss, RYGB is the gold standard for bariatric operations. The operation involves using a stapler to close off most of the stomach leaving a small pouch at the entrance. The small intestine is separated from the large one and joined to the stomach pouch.        
Besides causing significant weight loss, on the order of 70% excess weight loss (% EWL), RYGB brings about resolution of obesity related comorbidities in most patients, including most cases of type 2 diabetes, obstructive sleep apnea, hypertension and hyperlipidemia (Buchwald, Avidor, Braunwald, et al. JAMA, October 2004). Additional studies indicate a significant survival benefit for morbidly obese patient who undergo RYGB as compared with morbidly obese controls who do not undergo surgery (Chritou N, et al. Ann Surg, August 2004).
Staple line failures with ensuing weight regain have been found to occur many years after the procedure. As a result surgeons have responded by use of techniques designed to prevent this including transection of the stomach, in which the staple line is divided and the cut ends oversewn.
The complications of gastric bypass are much less severe than those of Malabsorptive procedures. Most large series studies report complications in two phases, those, which occur shortly after surgery, and those, which take a longer time to develop. The most serious acute complications include leaks at the junction of stomach and small intestine. Complications which develop later include narrowing of the stoma (the junction between stomach pouch and intestine), which results from scar tissue development. This opening is made to be about 10 mm in diameter, therefore a very little scarring will reduce the opening to a degree that affects the patients eating. Wound hernias occur in 5-10% and intestinal obstruction in 2% of patients, an incidence similar to that following any general surgical abdominal procedure. Metabolic complications that occur following RYGBP include anemia and calcium deficit, because essential nutrients for blood production (iron and vitamin B12) depend on the stomach for absorption, and because calcium is best absorbed in the duodenum which is bypassed.
With the advent of laparoscopic surgery, a minimal access surgical solution for morbid obesity was investigated in many centers. Surgeons in the US have developed laparoscopic techniques for performing a RYGB. These techniques are quite successful and currently over 75% of RYGB procedures are done laparoscopically. Complication rate is low and early results compare favorably with open RYBG. However, the technique is challenging, and is associated with a long learning curve of about 100 procedures.
Adjustable Gastric banding (AGB) represents a revival of horizontal gastroplasty in which a silicone band is placed around the stomach. There are two leading adjustable bands on the market today. One was developed jointly in Italy and in Belgium and the other in Sweden. The differences between the two are small. In both, a silicone band, with an inflatable cushion inside is placed around the stomach, and sutured in place. At a later date, the band is inflated to tighten the closure. If the patient gains weight, the band is inflated again. If the patient loses too much weight, the band is deflated. The long-term results of laparoscopic gastric banding are not known, but early results seem to compare well with other purely restrictive procedures such as SRVG or VBG described above.
An endoscopic procedure for reducing capacity has been proposed in U.S. Pat. No. 6,572,629 by Kalloo, et al. In this method a ligating loop is clipped either to the interior of the stomach or around the outside of the stomach and pulled tight and tied in order to effectively reduce the size of the stomach. The loop is attached to the interior walls of the stomach with a flexible endoscope introduced through the esophagus. The loop is attached on the outside of the stomach by creating an opening in the stomach and causing the end of the endoscope to exit the stomach into the peritoneal cavity. Some of the techniques used are described in an earlier patent, U.S. Pat. No. 7,721,742, by the same inventors.
To summarize the current state of the art of surgical options in the treatment of obesity, the ideal bariatric operation is one which is simple, carries few complications, and results in a predictable and sustained weight loss. Such an operation does not exist.
The best long-term results are 80% % EWL at 5 years, for the Biliary pancreatic bypass operation. However these results are achieved using a very complex operation, with a high complication rate in non-expert hands. The various restrictive and hybrid operations yield a two-year EWL of between 50% (AGB) and 65-70% (RYGB). These results are far superior to the results of non surgical treatment. Even the simplest gastric restrictive operation—stapled horizontal gastroplasty—is superior to diet alone. Long-term success rate varies between 30 and 60% versus, 10-15% for the most successful nonoperative schemes.
However, because of the complications of surgery: any of the above procedures is associated with some risk. For this reason the operative approach, using any of the known methods, is limited to the morbidly obese. In these patients the risks are justified, even with the imperfect results of surgery. Patients who are merely obese, and certainly overweight persons, are not candidates for any of these procedures. This mirrors the guidelines established by NIH in 1991 for weight loss surgery.
It is therefore a purpose of the present invention to provide bariatric procedures that overcome the shortcomings of the prior art.
It is another purpose of the present invention to provide bariatric procedures that are carried out endoscopically or laparoscopically.
It is a further purpose of the present invention to provide endoscopic and laparoscopic devices for carrying out bariatric procedures.
Further purposes and advantages of this invention will appear as the description proceeds.